mtd: atmel_nand: according to pmecc version to perform 0xff page correction

As the PMECC hardware has different version. In SAMA5D4 chip, the PMECC ip
can generate 0xff pmecc ECC value for all 0xff sector.

According to this, add PMECC version check, if it's SAMA5D4 then we always
let PMECC hardware to correct it.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>

drivers/mtd/nand/atmel_nand.c

@@ -44,6 +44,7 @@ struct atmel_nand_host {
 	u8		pmecc_corr_cap;
 	u16		pmecc_sector_size;
 	u32		pmecc_index_table_offset;
+	u32		pmecc_version;
 
 	int		pmecc_bytes_per_sector;
 	int		pmecc_sector_number;
@@ -486,6 +487,10 @@ static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf,
 	int i, err_nbr, eccbytes;
 	uint8_t *buf_pos;
 
+	/* SAMA5D4 PMECC IP can correct errors for all 0xff page */
+	if (host->pmecc_version >= PMECC_VERSION_SAMA5D4)
+		goto normal_check;
+
 	eccbytes = nand_chip->ecc.bytes;
 	for (i = 0; i < eccbytes; i++)
 		if (ecc[i] != 0xff)
@@ -961,6 +966,10 @@ static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
 	nand->ecc.write_page = atmel_nand_pmecc_write_page;
 	nand->ecc.strength = cap;
 
+	/* Check the PMECC ip version */
+	host->pmecc_version = pmecc_readl(host->pmerrloc, version);
+	dev_dbg(host->dev, "PMECC IP version is: %x\n", host->pmecc_version);
+
 	atmel_pmecc_core_init(mtd);
 
 	return 0;

drivers/mtd/nand/atmel_nand_ecc.h

@@ -123,6 +123,20 @@ struct pmecc_errloc_regs {
 	u32 sigma[25];	/* 0x28-0x88 Error Location Sigma Registers */
 	u32 el[24];	/* 0x8C-0xE8 Error Location Registers */
 	u32 reserved1[5];	/* 0xEC-0xFC Reserved */
+
+	/*
+	 * 0x100-0x1F8:
+	 *   Reserved for AT91SAM9X5, AT91SAM9N12.
+	 *   HSMC registers for SAMA5D3, SAMA5D4.
+	 */
+	u32 reserved2[63];
+
+	/*
+	 * 0x1FC:
+	 *   PMECC version for AT91SAM9X5, AT91SAM9N12.
+	 *   HSMC version for SAMA5D3, SAMA5D4. Can refer as PMECC version.
+	 */
+	u32 version;
 };
 
 /* For Error Location Configuration Register */
@@ -137,6 +151,12 @@ struct pmecc_errloc_regs {
 #define		PMERRLOC_ERR_NUM_MASK		(0x1f << 8)
 #define		PMERRLOC_CALC_DONE		(1 << 0)
 
+/* PMECC IP version */
+#define PMECC_VERSION_SAMA5D4			0x113
+#define PMECC_VERSION_SAMA5D3			0x112
+#define PMECC_VERSION_AT91SAM9N12		0x102
+#define PMECC_VERSION_AT91SAM9X5		0x101
+
 /* Galois field dimension */
 #define PMECC_GF_DIMENSION_13			13
 #define PMECC_GF_DIMENSION_14			14